Complex carbohydrates and polysaccharides have numerous functions in food products such as emulsifiers, emulsion stabilizers, thickening and gelling agents and suspending agents (Sandford and Baird, 1983). Most polysaccharides function by altering the properties of aqueous solutions or dispersions primarily via their ability to bind water molecules and ions; they also interact with each other through "junction zone" formation (Rees, 1972).
Several plant families include species that exude gums, and those that produce copious quantities represent a ready supply of gums. In addition to exudate gums, gums are also obtained from seeds, for example guar gum and from algae, e.g. agar. More recently, gums have been produced by microbial fermentation under controlled conditions, and xanthan gum which is produced in this manner has recently achieved commercial significance. In general, these gums or mucilages are carbohydrate-enriched polymers of high molecular weight composed of acidic and/or neutral monosaccharide building units joined by glycosidic bonds.
Gum arabic is the dried exudate from species of the acacia tree (Acacia senegal) found in various tropical and semitropical areas of the world. The acacia trees produce large quantities of gum arabic under adverse conditions, lack of moisture, poor nutrition and high temperatures. The gum is collected as a natural exudate from the surface of wounds generally produced deliberately in cultivated trees. The exudate is dried to form a product which is completely soluble in hot or cold water, yielding a viscous solution of mucilage finding wide use as a thickening agent and emulsion stabilizer in a wide range of foods, beverages and confectionery and also in adhesives, inks, textiles, printing and cosmetics.